A commercial airplane may include a lavatory, which typically includes a toilet and a washbasin or sink. A drain assembly is connected to the sink, and a drain valve may be in fluid communication with the drain assembly. Fluid drains from the sink via the drain assembly, and then flows through the drain valve. In some cases, the drain valve may become clogged, preventing use of the sink, requiring repair, and increasing aircraft maintenance costs. Instead of, or in addition to the drain valve becoming clogged, the drain assembly may become clogged, also preventing use of the sink, requiring repair, and increasing aircraft maintenance costs. Frequent clogging of the drain valve and/or the drain assembly may necessitate more maintenance intervals, thereby further increasing aircraft maintenance costs. Therefore, what is needed is an apparatus, assembly, kit, or method that addresses one or more of the foregoing issues, and/or one or more other issues.